Methods for coating a substrate with an amphiphilic compound

ABSTRACT

Methods of modifying a patterned semiconductor substrate are presented including: providing a patterned semiconductor substrate surface including a dielectric region and a conductive region; and applying an amphiphilic surface modifier to the dielectric region to modify the dielectric region. In some embodiments, modifying the dielectric region includes modifying a wetting angle of the dielectric region. In some embodiments, modifying the wetting angle includes making a surface of the dielectric region hydrophilic. In some embodiments, methods further include applying an aqueous solution to the patterned semiconductor substrate surface. In some embodiments, the conductive region is selectively enhanced by the aqueous solution. In some embodiments, methods further include providing the dielectric region formed of a low-k dielectric material. In some embodiments, applying the amphiphilic surface modifier modifies an interaction of the low-k dielectric region with a subsequent process.

PRIORITY CLAIM TO PROVISIONAL APPLICATION

This is a Continuation of U.S. patent application Ser. No. 12/172,110,filed on Jul. 11, 2008; which claims priority under the provisions of 35U.S.C. §119 to U.S. Provisional Application No. 60/949,773, filed onJul. 13, 2007; and to U.S. Provisional Application No. 60/949,798, filedon Jul. 13, 2007; and to U.S. Provisional Application No. 61/017,395,filed on Dec. 28, 2007, each of which is incorporated herein byreference for all purposes.

BACKGROUND

The semiconductor industry is increasingly moving to substratescomprising low-k dielectric materials in order to achieve continuedscaling of microelectronic devices. Low-k dielectric materials arecharacterized by having a low dielectric constant relative to silicondioxide, a common dielectric material. As microelectronic devices becomesmaller, the amount of dielectric material isolating conductive areasbecomes correspondingly smaller. In some conventional examples utilizingsilicon dioxide, thinning dielectric material may result in capacitiveeffects, cross-talk effects, and other undesirable effects thatadversely affect device performance. Replacing silicon dioxide withlow-k dielectric material of like thickness may reduce or eliminatethese detrimental effects.

Use of low-k dielectric materials, however, is not a panacea. Forexample, some portions of low-k dielectric materials (e.g., traceNH_((x)) groups), may adversely affect chemistries of subsequentsubstrate processing. In addition, many low-k dielectric materials lackfunctional groups, which may be required for covalent chemistry.Furthermore, low-k dielectric materials are characteristicallyhydrophobic, which makes surfaces of low-k dielectric materialsdifficult to wet. In some examples, this hydrophobic characteristic mayinhibit or altogether prevent aqueous (wet) processing steps fromreacting with conductive regions (i.e., copper lines) that may belocated directly adjacent with hydrophobic low-k dielectric materials.Some aqueous steps may include: aqueous cleaning steps, metallizationsteps, and other similar wet steps. While a hydrophobic characteristicmay be problematic for featureless substrates, it is especiallyproblematic for substrates having narrow topographical features such asvias and trenches.

For example, surface characteristics of patterned substrates, as may beappreciated, may present challenges to process integration in amanufacturing context. Where wet chemistries are utilized, a hydrophobicdielectric surface having a high wetting angle characteristic mayadversely affect adjoining conductive surfaces targeted by the wetchemistries. FIG. 1A is a prior art illustrative cross-sectional view ofa portion of a substrate 100A having a base layer 105A, conductiveregions 110A, and dielectric regions 120A with arrows 150A illustratinghydrophobic forces at the surface of the dielectric regions 120A. Thearrows 150A illustrated in FIG. 1A illustrate the outward force of thehydrophobic properties of the low-k dielectric in dielectric regions120A. Hydrophobic properties may present challenges in processintegration when utilizing aqueous semiconductor processes. Inparticular, when features are densely integrated having dielectricregions closely interleaved with conductive regions, dielectric regionshaving hydrophobic properties may hinder or altogether prevent aqueousreactions along conductive regions. One possible adverse result due tohydrophobic characteristics is that deposition rates may not be uniformor, in some example, may fail entirely on smaller more isolatedfeatures. Non-uniform thicknesses of deposited layers or failure todeposit layers may cause integration problems during subsequentsemiconductor processing as well as performance problems (e.g.,increased resistance in thinner depositions) when using a finisheddevice.

FIG. 1B is a prior art illustrative cross-sectional representation of anuntreated substrate 100B after a wet deposition process. As illustrated,substrate 100B may include a base layer 105B, dielectric regions 120B,and conductive regions 110B and 112B. A single layer is illustrated, butembodiments provided herein may equally apply to one or many layerswithout departing from the present invention. In some embodiments,substrate 100B may include an electronic device and may be made, inwhole or in functionally significant part, of semiconductor material ormaterials. As illustrated, conductive regions 110B and 112B anddielectric regions 120B are formed over base 105B, which may beconductive in some embodiments. Thus, for example, conductive regions110B and 112B may form interconnections between base 105B and otherelectrically conductive materials subsequently formed as part ofsubstrate 100B. Further, as illustrated, dielectric regions 120Brepresent areas having hydrophobic characteristics as indicated byarrows 150B. Hydrophobic characteristics may present challenges inprocess integration when using aqueous semiconductor processes. Inparticular, when features are densely integrated having dielectricregions closely interleaved with conductive regions, or when featuresare small or isolated, dielectric regions having hydrophobiccharacteristics may hinder or altogether prevent aqueous reactions alongconductive regions. Thus, one result of these hydrophobiccharacteristics is that depositions 114B and 116B may not have a uniformthickness, as illustrated, or may not even occur on the smaller moreisolated features. Non-uniform thicknesses of deposited layers orfailure to deposit may cause integration problems during subsequentsemiconductor processing as well as performance problems (e.g.,increased resistance in the thinner deposition 116B) when using afinished device. It should be noted that the illustrated thicknesses arenot drawn to scale and should not be construed as limiting with respectto scale or proportion.

In other examples, at least some low-k dielectric materials are porous.Porous low-k dielectric materials may, in some examples, trap unwantedmaterials (such as particles, solvents, etc. . . . ) that may adverselyaffect dielectric properties. During processing, dielectric surfaces maybe subjected to undesirable penetration of damaging process chemistriesinto underlying dielectric regions. In some cases, capacitance of thedielectric region may be adversely affected. The low-k dielectricmaterial may be physically damaged, degraded, or chemically altered insuch a way that the dielectric constant of the material is increased.For example, one class of process chemistries which are particularlyreactive with dielectric materials are surfactants. Surfactants, as maybe appreciated, are wetting agents that may be utilized to lower thesurface tension of a liquid and to allow easier spreading thus improvingreactivity of aqueous chemistries. However, surfactants may also havedamaging effects. In some examples a dielectric constant of a low-kdielectric material may be temporarily or permanently altered. As may beappreciated, porous low-k dielectric materials include pores thatfunction to lower the dielectric constant of a dielectric material.Certain processing materials such as surfactants may enter and fill thepores of the dielectric material changing the dielectric constant of thedielectric.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings and in whichlike reference numerals refer to similar elements and in which:

FIGS. 1A-B, are prior art illustrative cross-sectional views of aportion of a substrate having a base layer, conductive regions, anddielectric regions;

FIG. 2 is an illustrative flowchart of methods for modifying a substratein accordance with embodiments of the present invention;

FIGS. 3A-C, are illustrative cross-sectional views of a portion of asubstrate having a base layer, conductive regions, and dielectricregions in accordance with embodiments of the present invention;

FIG. 4 is an illustrative representation of an amphiphilic moleculeformed on a dielectric region of a substrate in accordance withembodiments of the present invention;

FIG. 5 is an illustrative cross-sectional view of a portion of asubstrate having an electrically conductive region, at least twodifferent dielectric regions and, a formed amphiphilic layer inaccordance with embodiments of the present invention;

FIG. 6 is an illustrative representation of substrate and an explodedview of an amphiphilic surface modifier layer formed on non-porous low-kdielectric material in accordance with embodiments of the presentinvention;

FIG. 7 is an illustrative representation of substrate and an explodedview of an amphiphilic surface modifier layer formed on porous low-kdielectric material in accordance with embodiments of the presentinvention;

FIGS. 8A-B are illustrative representations of an untreated substrateand treated substrate and accompanying graphical representation ofatomic force microscope (AFM) scan in accordance with embodiments of thepresent invention;

FIG. 9 is an illustrative graphical representation of thickness bysample in accordance with embodiments of the present invention;

FIG. 10 is an illustrative graphical representation of thickness bysample in accordance with embodiments of the present invention; and

FIG. 11 includes illustrative graphical representations of % capacitancechange by type in accordance with embodiments of the present invention.

DETAILED DESCRIPTION

The present invention will now be described in detail with reference toa few embodiments thereof as illustrated in the accompanying drawings.In the following description, numerous specific details are set forth inorder to provide a thorough understanding of the present invention. Itwill be apparent, however, to one skilled in the art, that the presentinvention may be practiced without some or all of these specificdetails. In other instances, well known process steps and/or structureshave not been described in detail in order to not unnecessarily obscurethe present invention.

Embodiments of the current invention describe a surface modifier tomodify low dielectric constant materials. It is becoming increasinglydesirable to use low dielectric constant (k), or “low-k” dielectricmaterials in the manufacture of microelectronic devices to, for example,provide a reduction in capacitive and cross-talk effects. A low-kdielectric material is one having a dielectric constant of lower than3.9. The surface of the low-k dielectric can be modified to improve itsinteraction with subsequent solutions applied to the surface. In oneembodiment, the surface of the low-k dielectric is modified to improvethe wettability of the low-k dielectric material to an aqueous solution.In another embodiment, the surface of a porous low-k dielectric materialis modified to seal the pores to prevent the diffusion of chemistries ormaterials into the pores. Embodiments of inventive surface modifiers arealso disclosed as well as methods of using those surface modifiers.

FIG. 2 is an illustrative flowchart of methods for modifying a substratein accordance with embodiments of the present invention. At block 201 ofFIG. 2, the method provides a patterned semiconductor substrate surfacecomprising a dielectric region and a conductive region. An examplepatterned substrate is illustrated in FIG. 3A, which is an illustrativecross-sectional view of a portion of a substrate 300A having a baselayer 305A, conductive regions 310A, and dielectric regions 320A inaccordance with embodiments of the present invention. Embodiments mayinclude any number of layers or regions in any configuration withoutdeparting from the present invention. In some embodiments, conductiveregions 310A may be formed from copper, aluminum, and copper alloys suchas copper-zinc alloys, copper-calcium alloys, and copper-manganesealloys, or some combination thereof without departing from the presentinvention. In addition, dielectric regions 320A may be formed from alow-k dielectric material that is formed from a doped or otherwisemodified silicon dioxide-based material (SiO₂) or other dielectricmaterials without departing from the present invention. The dielectricconstant of SiO₂ (3.9) can be lowered by utilizing methods such asdoping with fluorine to produce fluorinated silica glass (FSG), whichhas a dielectric constant of 3.5. In some embodiments, other low-kdielectric materials may include: SiCN, SiCNH, SiCH₃, SiOCH₃, SiCOH,porous SiCOH, SiN, SiC, SiO₂, methyl-silsesquioxane (MSQ), SiLKdielectric by Dow Chemical, parylene, organic low-k polymers, and othersimilar materials. Additionally, dielectric regions may include a hardmask layer (not shown) at the surface of the low-k dielectric regions,which is often formed of a silicon-based material like SiC_(x), SiN_(x),SiC_(x)N_(y), etc., where the variables x and y represent values asappropriate to desired compositions. The low-k dielectric materials arehydrophobic to different extents. For example, the low-k dielectricmaterial may include methyl (—CH₃) or ethyl (—C₂H₅) groups, for example,that increase the hydrophobic nature of the substrate as illustrated bythe arrows 150A in FIG. 1A.

Returning to FIG. 2, at block 202 the method forms a solution comprisingan amphiphilic surface modifier. The amphiphilic surface modifier may bea polyvinyl alcohol (PVA), an amphiphilic macromolecule, a modifiedstarch compound, a protein compound, a diblock copolymer, a triblockcopolymer, or a dendrimers. As utilized herein, amphiphilic is a termdescribing a chemical compound possessing both hydrophilic andhydrophobic properties. The amphiphilic surface modifiers can also betailored to have certain chemical properties and size for differentapplications. For example, because the surface modifier is amphiphilic,the solution may be formulated to adjust the wetting angle of a surface.In other embodiments, the amphiphilic surface modifier may be selectedto be relatively large molecules (macro-molecules) to block pores and toprevent or minimize diffusion of any wet process compounds into blockedpores. In yet another embodiment, amphiphilic compounds may be utilizedto protect porous low-k dielectric materials from subsequent processes.

Referring to FIG. 3B, in embodiments, hydrophobic low-k dielectricregions 320B may be modified by the application of a formulation thatincludes an amphiphilic surface modifier resulting in a surface havinghydrophilic characteristics. In one embodiment, amphiphilic surfacemodifier 330B comprises a PVA surface modifier that is applied tosubstrate 300B in an aqueous application step. PVA is a water-solublesynthetic polymer that features advantageous film forming, emulsifying,and adhesive properties. Amphiphilic surface modifiers can be selectiveto the dielectric regions 320B depending upon composition and processtimes. Amphiphilic compositions may be selected that do not generallyadhere to conductive (e.g., copper) surfaces, but instead adhereselectively to hydrophobic dielectric surfaces. In other embodiments,however, an amphiphilic surface modifier may be non-selectively formedon both dielectric regions and to conductive regions. In someembodiments, PVA compounds containing thiol (e.g. polyvinyl mercaptan)or amine (e.g. polyvinylamine) functionality will adhere non-selectivelywith conductive regions as well as dielectric regions. In anon-selective example, an amphiphilic layer formed on a conductiveregion may require removal before subsequent aqueous processes. In someembodiments, amphiphilic layers may be further composed of amphiphilicmacromolecules, modified starch compounds, protein compounds, diblockcopolymers, triblock copolymers, and dendrimers in any combinationwithout departing from the present invention.

In order to formulate an amphiphilic PVA surface modifier, PVA may befirst dissolved in water at a sufficiently high temperature (e.g., 25 to90° C.) to prepare an aqueous PVA solution. As described above, otheramphiphilic compounds, such as starches, may also be used in addition toor instead of PVA. Once a PVA solution is fully dissolved, the PVAsolution may be allowed to cool to approximately room temperature beforeapplication. The concentration of the PVA solution and the processparameters related to the reaction process, such as time of formation(reaction period) prior to rinsing, temperature of solution, pH ofsolution, and so on, depend generally upon the requirements of theprocessing steps to which a substrate is subjected. In some embodiments,a PVA solution may be prepared having a concentration in the range ofapproximately 1 to 500 mM, more preferably 25 to 100 mM. It should benoted that the example concentrations (e.g., 25 mM) are stated withrespect to monomer units, and not with respect to entire molecules oflength, n. Thus, a particular molecular weight of an amphiphiliccompound may be selected to address particular semiconductor processingsteps and circuit geometries.

Unlike most vinyl polymers, PVA is not prepared by polymerization of acorresponding monomer. The monomer, vinyl alcohol, almost exclusivelyexists as the tautomeric form, acetaldehyde. PVA instead is prepared bypartial or complete hydrolysis of polyvinyl acetate to remove acetategroups. For embodiments in which an amphiphilic surface modifiercomprises PVA, fully hydrolyzed PVA may be used. Without being bound bytheory, the percentage of hydrolysis may affect how strongly a PVAcompound may attach with a surface. It is theorized that higher levelsof hydrolysis may result in stronger attachment by a PVA compound with adielectric surface. However, depending upon the application, the amountof hydrolysis can also be changed, for example from 75% to 100%hydrolyzed PVA. In some embodiments, an amphiphilic PVA surface modifierthat is not fully hydrolyzed may include polyvinyl acetate. It isunderstood, however, that any amount of hydrolysis may be utilizedwithout departing from the present invention. PVA may also be fully orpartially functionalized with a desired functional group, such as thiols(—SH) or amines (—NH). For example, thiols can be used to grow metals onthe PVA surface. Once a PVA solution is fully dissolved, the PVAsolution may be allowed to cool down to approximately room temperaturebefore application.

In some embodiments, PVA and cationic starches may be selected to forman amphiphilic layer for at least the following reasons: theseamphiphilic compounds do not chemically react with low-k dielectricmaterials; these amphiphilic compounds are water soluble; and theseamphiphilic compounds may be readily removed in a high temperature(e.g., greater than 80° C.) rinsing step. It may be noted that althoughsubsequent discussion may be directed to amphiphilic surface modifierscomposed of PVA, it should be noted that such discussion applies equallyto other amphiphilic compounds such as: starches, modified starches(e.g., cationic, anionic), proteins, and other similar compounds thatcan render a hydrophobic surface hydrophilic without departing from thepresent invention. Additionally, mixtures of PVA and starches may beutilized in any combination without departing from the presentinvention.

In some embodiments, PVA may further be co-polymerized with otherpolymers, which may provide additional protection for some processchemistries. Co-polymers may include: co-ethylene, co-cation,co-siloxane, co-anion (88% hydrolyzed), and co-anion (80% hydrolyzed).Without being bound by theory, it is proposed that a co-polymer complexmay form a more robust covalent bond with surface groups on thedielectric material. Copolymerization may, in some embodiments, beutilized to tailor a surface modification layer to protect the low-kdielectric layer from particular chemistries of solutions applied insubsequent processing. For example a PVA-co-siloxane surfacemodification layer can prevent the degradation of a low-k dielectriclayer during a post-CMP cleaning step where a non-fluorinated, highperformance copper/low-k CMP cleaning solution such as CoppeReady CP72Bby Air Products and Chemicals, inc. of Allentown, Pa. is used.

In addition, the molecular weight of PVA may be tailored to specificprocessing needs (or pore size). Accordingly, amphiphilic compounds foruse with non-porous low-k dielectric materials may be small molecularcompounds (for example, having a molecular weight in the range of 5 to200 kiloDaltons (kDa). Amphiphilic compounds for use with porous low-kdielectric materials may be macro-molecular compounds. For example,depending on a pore size of a low-k dielectric material, PVA may betailored to have a molecular weight in the range of approximately 5 to500 kDa. In a preferred embodiment, a 25 mM with respect to monomersolution of a PVA compound having a molecular weight in a range ofapproximately 13-23 kDa where the PVA compound is 99% hydrolyzed. Inaddition, for substrates having topographical features that include viasand trenches, a PVA layer formed on a low-k dielectric material inaccordance with embodiments provided herein, may enhance post via etchcleaning processes by enabling cleaning solutions to clean otherwiseunreachable residues from via bottoms. Further aspects of amphiphilicsurface modifiers will be discussed in further detail below for FIGS.4-7.

In some embodiments, prior to applying the surface modifier on theexposed surfaces of the substrate (such as substrate 300A, FIG. 3A), thesubstrate surface may be prepared for processing in a preparationprocess that contains at least one or more cleaning steps (e.g., adeionized water rinse and/or any of a variety of other well-knownsurface cleaning step(s)) to remove contaminants left from previousprocessing. In one embodiment, the substrate 200 may be cleaned withdeionized water for 30 s. Alternatively, the application and rinsing ofthe surface modification solution layer may itself constitute a cleaningstep that prepares the substrate for a subsequent aqueous process step.

Returning to FIG. 2, at a block 203 an amphiphilic surface modifier isapplied to the surface of the low-k dielectric material 320A of thesubstrate 300A. An amphiphilic surface modifier solution may be appliedto the surface of a substrate in any manner known in the art withoutdeparting from the present invention. Generally, an amphiphilic surfacemodifier solution is applied to an entire surface of a substrate. Inembodiments, a PVA surface modifier will generally only adhere tohydrophobic dielectric regions. In some embodiments, an amphiphilicsurface modifier solution may selectively adhere to dielectric regionsof a substrate and not to conductive regions, thus conditioningdielectric surfaces. In selective applications, to the extent that anystray amphiphilic material adheres to conductive regions, such materialmay be removed in a subsequent step. After application, the amphiphilicsurface modifier solution is allowed to react with the substrate surfacefor a selected reaction period to form an amphiphilic surface modifierlayer 330B over the dielectric regions 320B as illustrated in FIG. 3B,which is an illustrative cross-sectional representation of surfacemodified substrate 300B after applying an amphiphilic surface modifierin accordance with embodiments of the present invention. As illustrated,substrate 300B may include a base layer 305B, dielectric regions 320B,and conductive regions 310B and 312B. As above, conductive regions 310Band 312B and dielectric regions 320B are formed over base 305B, whichmay be conductive in some embodiments. Thus, for example, conductiveregions 310B and 312B may form interconnections between base 305B andother electrically conductive materials subsequently formed as part ofsubstrate 300B. Substrate 300B includes layer 330B, which attaches withdielectric region or surface 320B. Layer 330B may be a PVA surfacemodifier (optionally removable) or other amphiphilic surface modifiers,such as cationic starches, protein compounds, diblock copolymers,triblock copolymers, dendrimers, and amphiphilic macromolecules can beused in any combination, or additionally in combination with PVA. Layer330B is preferably an amphiphilic surface modifier used to increase ahydrophilicity of the substrate 300B. Layer 330B reduces the contactangle of the surface of the dielectric region 320B, thereby increasingthe hydrophilic nature of the substrate 300B allowing better access ofaqueous processes to the conductive region 312B and 314B.

In this illustration the amphiphilic surface modifier selectivelydeposits on only the dielectric regions 320B, but the deposition mayalso be non-selective. In some embodiments, a selected reaction periodis less than approximately 300 seconds (s), and more preferably lessthan approximately 120 s. In some embodiments, a selected reactiontemperature is less than approximately 100° C., more preferably lessthan approximately 80° C. Layers comprising other amphiphilic surfacemodifiers may require different reaction periods for reactingamphiphilic layers. The thickness of the layer may also be selected inaccordance with requirements of a processing system. In general, theamphiphilic surface modifier may be formed in a layer of any thicknessand typically ranges from 5 to 50 Angstroms (Å), more preferably 20 to35 Å. In some embodiments, for example when the amphiphilic surfacemodifier comprises PVA, the amphiphilic surface modifier is very thinlayer, on the order of 20 to 35 Å. Therefore, in these embodiments, theamphiphilic surface modifier may or may not be removed after subsequentaqueous processing, since a thin layer may not affect further processingor the final semiconductor device.

In order to more fully clarify embodiments of the present invention,FIG. 4 illustrates a representation of an amphiphilic molecule formed ona dielectric region of a substrate in accordance with embodiments of thepresent invention, amphiphilic molecule 402 is formed on the surface ofdielectric material 410. Amphiphilic molecule 402 contains hydrophilicportion 404 and hydrophobic portion 406 connected along backbone 412. Itmay be appreciated that backbone 412 represents a connective bond andmay include additional functional groups without limitation and withoutdeparting from the present invention.

As illustrated, any number of molecules (n) may comprise a polymericamphiphilic layer. In one embodiment, a hydrophilic portion of a PVAmolecule includes a number of —OH functional groups, which account forthe hydrophilic nature of the molecule. In embodiments, a hydrophobicportion of a PVA molecule may weakly bond with the surface of dielectricmaterial 410 as illustrated by bonding force 408. Furthermore,hydrophobic portions 406 do not readily attach with conductive surfaces(not shown) in some embodiments and, as such, amphiphilic compounds maybe selected to selectively adhere with dielectric surfaces. As may beseen, when amphiphilic molecule 402 is attached with surface ofdielectric material 410, hydrophilic portion 404 of amphiphilic molecule402 is oriented to provide an exposed hydrophilic surface. Amphiphilicmolecule 402 may bond with dielectric surface through any theoreticallypossible means including chemical bonding, physical bonding or any othermechanism or force without departing from the present invention. In thismanner, an amphiphilic molecule may effectively lower the wetting angleof dielectric material 310 surface thus facilitating aqueous processingof adjacent conductive surfaces.

In another embodiment, FIG. 5 is an illustrative cross-sectional view ofa portion of an alternate substrate 500 having an electricallyconductive region 506, at least two different dielectric regions 502 and504, and an amphiphilic surface modifier layer 508 in accordance withembodiments of the present invention. For substrates havingtopographical features that include vias and trenches, an amphiphilicsurface modifier layer formed on a low-k dielectric material or multipledielectric materials in accordance with embodiments provided herein, mayenhance post via etch cleaning processes by enabling cleaning solutionsto clean otherwise unreachable residues from via bottoms. As shown inFIG. 5, substrate 500 includes a dual damascene feature that consists ofa first dielectric layer 502 having a first dielectric constant, and asecond dielectric layer 504 having a second dielectric constant.Substrate 500 may also include etch stop, hard mask, and other layerswith different surface characteristics as well, which are not shownhere. At the bottom of the trench/via is conductive region 506. As shownin FIG. 5, one or both of dielectric layers 502 and 504 may be low-kdielectric materials, and are therefore at least partially hydrophobic.In addition, one or both layers 502 and 504 may be porous or non-porous.As such, a subsequent aqueous process be inhibited or altogetherprevented from reaching conductive region 506 at the bottom of thetrench/via due to the repulsive effect on an aqueous solution caused bythe hydrophobic nature of the trench/via walls of layers 504 and 502prior to treatment, especially when the trench/via have a high aspectratio. To counteract this effect, an amphiphilic layer 508 is formed onboth hydrophobic dielectric regions. Thus, amphiphilic layer 508provides a same or similar wetting angle for all portions of the featureand allows any subsequent aqueous processes to effectively reachconductive region 506 at the bottom of the trench/via. Amphiphilicsurface modifier layer 508 may be a PVA layer (optionally removable) orother amphiphilic layers, such as cationic starches, protein compounds,diblock copolymers, triblock copolymers, dendrimers, and amphiphilicmacromolecules can be used in any combination, or additionally incombination with PVA.

As described above, the amphiphilic layer 508 will deposit and reactwith hydrophobic surfaces of the feature to impart a hydrophiliccharacteristic. If one or more surfaces of the feature are porous, apore-sealing effect of the amphiphilic layer will also serve tocondition the substrate to prevent or minimize diffusion of processmolecules through pores in dielectric regions. The use of an amphiphiliclayer to change a hydrophobic characteristic of a substrate or ofsubstrate portions can be particularly useful in complex, small scaletopographical features where aqueous processes may be prevented fromentering and accessing hydrophobic lined trenches/vias, as shown in FIG.5.

FIG. 6 is an illustrative representation of substrate 600 and anexploded view 610 of amphiphilic surface modifier layer 612 formed onnon-porous low-k dielectric material 602 in accordance with embodimentsof the present invention. Substrate 600 may include any number ofdielectric regions 602 and 606 along with conductive region 604, whichmay be interleaved and configured in any fashion without departing fromthe present invention. Exploded view 610 particularly illustratesnon-porous dielectric surface 620 after treatment utilizing embodimentsdescribed herein. As illustrated, amphiphilic surface modifier layer 612attaches along dielectric surface 620. It may be noted that amphiphilicsurface modifier layer 612 may bond with dielectric surface 620 throughany theoretically possible means including chemical bonding, physicalbonding or any other mechanism or force without departing from thepresent invention. Thus, dielectric region 602 may be protected whileleaving conductive region 604 relatively accessible to processchemistries. As illustrated, amphiphilic surface modifier layer 612 is amonolayer. However, in some embodiments, additional layers may be formedwithout departing from the present invention. In some examples utilizingaqueous processes, non-porous dielectric materials may suffer frompenetration of process chemistry through the dielectric surface, whichmay adversely alter the dielectric's properties or may cause shortingbetween conductive regions. When utilizing an amphiphilic surfacemodifier layer as illustrated, methods are provided which protectdielectric surfaces with a surface modifier, thus allowing aqueousprocesses to proceed without damaging an underlying porous dielectricmaterial.

FIG. 7 is an illustrative representation of substrate 700 and anexploded view 710 of amphiphilic surface modifier layer 712 formed onporous low-k dielectric material 702 in accordance with embodiments ofthe present invention. Substrate 700 may include any number ofdielectric regions 702 and 706, along with conductive region 704, whichmay be interleaved and configured in any fashion without departing fromthe present invention. Exploded view 710 particularly illustratesdielectric surface 720 after treatment. As illustrated, amphiphilicsurface modifier layer 712 attaches along dielectric surface 720. Asabove, amphiphilic surface modifier layer 712 may bond with dielectricsurface 720 through any theoretically possible means including chemicalbonding, physical bonding or any other mechanism or force withoutdeparting from the present invention. Thus, dielectric region 702 may beprotected while leaving conductive region 704 relatively accessible toprocess chemistries. As illustrated, amphiphilic surface modifier layer712 is a monolayer (i.e. a single layer of PVA molecules). However, insome embodiments, additional layers may be formed without departing fromthe present invention. Further, as illustrated, amphiphilic surfacemodifier layer 712 may be formed over pores 730 which may be presentalong surface of dielectric region 702. Porous dielectric material maybe utilized to reduced undesirable capacitive and cross-talk effects.However, in some examples utilizing aqueous processes, porous dielectricmaterials may suffer from diffusion of chemistry into the pores, whichmay adversely alter the dielectric's properties (such as increasing thedielectric constant) or may cause shorting between conductive regions.When utilizing an amphiphilic surface modifier layer as illustrated,methods are provided which cover pores without filling them, thusallowing aqueous processes to proceed without damaging an underlyingporous dielectric material. In some embodiments, a size or molecularweight of the amphiphilic surface modifier layer can be chosen dependingon the porosity of the dielectric region 702. For example, in oneembodiment, a PVA surface modifier layer may include molecular weightsranging from 5 to 500 kiloDaltons (kDa), the particular weight utilizeddepending on the chosen dielectric material.

Returning to FIG. 2, at block 204 the amphiphilic surface modifier mayoptionally be cross-linked. In some embodiments, amphiphilic surfacemodifiers may be modified through cross-linking or similar processes toincrease stability of the layer. In addition, in some embodiments,cross-linking may include creating functional handles to allowpost-deposition modification. In some embodiments, cross-linkingprocesses may be performed by chemical modification. Chemicalmodification processes may be facilitated by creation of hydrophilicfunctional handles as provided by an amphiphilic layer. Cross-linkingagents that may be utilized for chemical modification include: aglutaraldehyde solution, a dialdehyde solution, a sulfuric acid (H₂SO₄)solution, a maleic acid solution, a citric acid solution, a solution ofglutaraldehyde and sulfuric acid, and an ascorbic acid solution withoutdeparting from the present invention. In some embodiments, cross-linkingprocesses may be performed by non-chemical modification. Non-chemicalmodification may include: deep ultra-violet (DUV) cure, ebeam cure, orplasma cure methods without departing from the present invention. Inaddition, in some embodiments, cross-linking may also change the contactangle of a treated substrate thus further altering the wettability ofthe treated surface. In some embodiments, cross-linking may affect athickness of an amphiphilic layer. In addition, in embodiments utilizingPVA, cross-linking of a PVA surface modifier may occur over a selectedcross-linking period in the range of approximately 30 to 600 s at atemperature in a range of approximately 25 to 60° C. Layers comprisingother amphiphilic compounds may require different cross-linking periodsfor cross-linking amphiphilic layers.

Cross-linking may provide a more stable amphiphilic surface modifierlayer to protect a low-k dielectric surface during subsequentprocessing. For example, in some applications, where harsh aqueousprocesses (e.g., high temperature processes) are anticipated or wheresurfactants are used, cross-linking amphiphilic surface modifiers mayprovide additional benefits. It has been experimentally determined thatcross-linking a PVA surface modifier can protect a low-k dielectric fromaggressive surfactants. In addition, cross-linking may also improve thepore-sealing characteristics of an amphiphilic surface modifier byimproving barrier properties of the layer.

At a block 205 of FIG. 2, the substrate may optionally be rinsed toremove excess amphiphilic surface modifier and any other contaminants.Rinsing may be accomplished utilizing any method well-known in the artwithout departing from the present invention. Rinsing may be utilized toclean surfaces of residual particles which may, in some examples, createnucleation sites that promote undesirable deposition. In one embodiment,in order to prevent removal of all PVA surface modifier solution(including PVA surface modifier bound with hydrophobic dielectricmaterial surface), a rinse step may be accomplished utilizing an aqueoussolution at a temperature lower than what is required to dissolve PVA.In some embodiments, a PVA surface modifier treated substrate may alsobe blown dry with, for example, nitrogen (N₂) or argon gas. After arinsing step, PVA surface modifier will have coated hydrophobic surfacesas illustrated in FIG. 2C. In some embodiments, the layer only grows toa certain size (e.g., ˜20 to 35 Å), and excess solution does not attach.In such an embodiment, the rinse will remove the excess PVA surfacemodifier.

At a next block 207 of FIG. 2, an aqueous process is performed on asubstrate having an amphiphilic surface modifier layer. Any aqueousprocess known in the art may be utilized without departing from thepresent invention including: an electrochemical deposition process, acleaning process, a pre-chemical mechanical planarization (CMP) cleaningprocess, a post-CMP cleaning process, a via cleaning process, a contactcleaning process, a trench cleaning process, a metallization process,and an electroless (e-less) deposition process. It may be appreciatedthat these processes may be selected in any combination to selectivelyreact with conductive regions that are not covered by an amphiphilicsurface modifier such as PVA.

In addition, in any of these aqueous processes, surfactants may beutilized to enhance the wettability of the substrate surface. A PVAsurface modifier may protect the low-k dielectric materials from damagedue to surfactant exposure. For example, a PVA surface modifier formedof a 0.5M solution of PVA compound having a molecular weight in therange of approximately 13 to 23 kDa and being 89% hydrolyzed and appliedto a porous low-k dielectric material may be utilized to protect low-kdielectric material from various concentrations of the non-ionicsurfactant PEG-PPG-PEG. The PVA surface modifier may be utilized toprotect a porous low-k dielectric material from concentrations ofgreater than 10% PEG-PPG-PEG up to 80% PEG-PPG-PEG.

In some embodiments, an aqueous deposition process may include anelectroless (e-less) deposition process. E-less deposition is thechemical deposition of a conductive material onto a base materialsurface by reduction of metal ions in a chemical solution withoutapplying an external electric potential. In some embodiments, e-lessdeposition is utilized to deposit a capping layer, such as a noble metal(eg. platinum (Pt) or ruthenium (Ru)), a cobalt (Co) layer, a nickel(Ni) layer, or an alloy such as CoWB, CoWPB, CoWP, on a conductiveregion of a substrate. A capping layer may be utilized to reduce orprevent electromigration from copper or other metallization (e.g.,conductive regions 310B, FIG. 3B) into other regions or layers. Using aPVA surface modifier may promote more even growth of a capping layer,improving integration of the capping layer. Referring briefly to FIG.3C, which is an illustrative cross-sectional representation of surfacemodified substrate 300C after a wet deposition process in accordancewith embodiments of the present invention, when layer 330C isselectively formed on dielectric regions 320B, an aqueous depositionprocess may be utilized to deposit a capping layer 332C on conductiveregions 310C.

As illustrated, substrate 300B may include a base layer 305B, dielectricregions 320B, and conductive regions 310B and 312B. As above, conductiveregions 310B and 312B and dielectric regions 320B are formed over base305B, which may be conductive in some embodiments. As above, conductiveregions 310B and 312B may form interconnections between base 305B andother electrically conductive materials subsequently formed as part ofsubstrate 300B. Substrate 300B includes layer 330B, which attaches withdielectric region or surface 320B. Layer 330B may be a PVA surfacemodifier (optionally removable) or other amphiphilic surface modifiers,such as cationic starches, protein compounds, diblock copolymers,triblock copolymers, dendrimers, and amphiphilic macromolecules can beused in any combination, or additionally in combination with PVA. Layer330B is preferably an amphiphilic surface modifier used to increase ahydrophilicity of the substrate 300B. In some embodiments, for examplelayer 330B is very thin, in the range of approximately 5 to 50 Å andpreferably within the range of approximately 20 to 35 Å. Therefore, inthese embodiments, layer 330B may or may not be removed after subsequentaqueous processing, since a thin layer may not affect further processingor the final semiconductor device. In an embodiment utilizing PVA, a PVAsurface modifier may be removed by rinsing a surface of a substrate witha hot water bath or during a hot water rinse process.

Returning to FIG. 2, at a next block 208, an amphiphilic surfacemodifier may be removed from a substrate in an aqueous rinse step. Anamphiphilic surface modifier layer may be generally removed by rinsing asurface of a substrate with a hot water bath or a hot water rinseprocess. In some embodiments, an aqueous process may remove all or partof an amphiphilic surface modifier layer. However, in embodiments wherecomplete removal is desirable, the method continues to remove allamphiphilic surface modifier. In one embodiment, the removal stepconsists of soaking or rinsing the substrate in an aqueous solution suchas a hot water bath for a specified removal period. In some embodimentsutilizing PVA, a removal temperature of an aqueous solution or hot waterbath is in the range of approximately 60 to 90° C. and a removal periodis approximately 60 s. Layers comprising other amphiphilic compounds mayrequire different temperatures and removal periods for removing anamphiphilic layer from a substrate after aqueous processing. In someembodiments, PVA may be removed in a plasma chamber before a subsequentprocess (e.g., deposition or pretreatment).

EXPERIMENTAL RESULTS I. Modifying Surface Characteristics

In some embodiments in which the amphiphilic surface modifier comprisesPVA, several specific examples of deposited PVA surface modifiers aredescribed herein. As used herein the term “deposited” and any derivationthereof broadly refers to the formation of a layer or region in anymanner known in the art and may include all such manners withoutdeparting from the present invention. Such examples are provided forpurposes of description only and represent unique instances of certainembodiments.

Experiment 1

Deposited PVA surface modifiers exhibit a reduced contact angle, andtherefore increased wettability and improved suitability for aqueousprocessing. A first example of a deposited PVA surface modifier wasformed by depositing three samples (denoted Sample 1, Sample 2, andSample 3) with each of four different PVA concentrations (25, 100, 250,and 500 mM), using a water deposition (0 mM) as a control.

With these examples, the PVA surface modifier solution was deposited for120 s, at 25° C. followed by a 60 s deionized water rinse. Each PVAsurface modifier solution was a PVA solution having a molecular weightin the range of approximately 13 to 26 kDa and being 99% hydrolyzed. Thedeposition produced a film having measurable thickness and contact angleparameters. The thickness of the layers was measured using ellipsometrytechniques, and the contact angle of the surface was measured toevaluate wettability.

The thickness measurements (in Angstroms) are as follows:

TABLE 1 0 mM (Water) 25 mM 100 mM 250 mM 500 mM Sample 1 8.98 23.7827.76 31.54 34.34 Sample 2 6.47 23.15 25.65 31.97 34.32 Sample 3 5.1023.64 30.37 31.27 33.18

As may be seen, compared with the control (water), all PVA surfacemodifiers show an increase in thickness, indicating that the PVA surfacemodifier has been deposited.

The contact angle (in degrees) measurements are as follows:

TABLE 2 0 mM (Water) 25 mM 100 mM 250 mM 500 mM Sample 1 67.4 39.3 36.136.3 33.8 Sample 2 80 41.5 39.6 34 33.7 Sample 3 82.4 39.5 35.3 35.734.2

As may be seen in the above table, all PVA surface modifiers show asubstantial contact angle reduction (i.e., an increase in thehydrophilic nature of the substrate) as compared with the control(water). Embodiments of amphiphilic surface modifiers may be utilizedwith substrates of various topographies and geometries. For example, ina dual damascene structure, a trench/via may be formed within a featurethat contains two layers that have different dielectric constants.

FIG. 8A is an illustrative representation of an untreated substrate 800and accompanying graphical representation of atomic force microscope(AFM) scan 810 for untreated substrate 800 in accordance withembodiments of the present invention. AFM is a very high-resolution typeof scanning probe microscope, with demonstrated resolution of fractionsof a nanometer. It should be noted that the graphical representationshown is intended for further clarifying and illustrating embodiments ofthe present invention and does not represent actual data, although theillustrated representation is consistent with experimental data. Itshould further be noted that illustrations are not necessarily drawn toa particular scale, but are provided for clarity in understandingembodiments described herein. Thus, illustrations provided should not beconstrued as limiting with respect to scale and proportion

As illustrated, untreated substrate 800 may include any number offeatures 802 (as indicated by cross-hatching) which may, in someexamples, be small and isolated with respect to other features, but maydensely populate a substrate nevertheless. Features 802 represent asubstrate having varying pattern density, or having conductive regionsthat have varying size and separation. Scan line 806 represents a pathof an AFM. AFM scan 810 illustrates a relative height of materialdeposited over features 802. Reference point 804 is provided for clarityin understanding AFM scan 810. As can be seen, where features aresmaller, less material is deposited, though under certain conditions, nomaterial will be deposited on the smaller features. This characteristicdeposition pattern may be due in part to hydrophobic characteristics ofdielectric portion 808, which may adversely affect aqueous depositionprocesses like electroless deposition.

FIG. 8B is an illustrative representation of a treated substrate 820 andaccompanying graphical representation of AFM scan 830 for treatedsubstrate 820 in accordance with embodiments of the present invention.As above, treated substrate 820 may include any number of features 822(as indicated by cross hatching) which may, in some examples, be smalland isolated with respect to other features, but may densely populate asubstrate nevertheless. Scan line 826 represents a path of an AFM. AFMscan 830 illustrates a relative height (i.e., thickness) of depositionover features 822. Reference point 824 is provided for clarity inunderstanding AFM scan 830. As may be seen for AFM scan 830, depositionrates for all features are more uniformly distributed. Thus, methodsprovided herein allow small features isolated by dielectric material tobe equally processed utilizing aqueous deposition processes. It shouldbe understood that features may also include topography, such as vias ortrenches. In those examples, AFM scanning measurements would then relateto the adequacy of the fill of those features.

II. Protecting Dielectric Materials

For embodiments in which the protective coating comprises PVA, severalspecific examples of deposited PVA layers are described herein. As usedherein the term “deposited” and any derivation thereof broadly refers tothe formation of a layer or region in any manner known in the art andmay include all such manners without departing from the presentinvention. Such examples are provided for purposes of description onlyand represent unique instances of certain embodiments.

Experiment 2

Experiment 2 demonstrates that cross-linking of a PVA surface modifierenhances the protection of the low-k dielectric from surfactants. Inorder to determine whether solutions containing surfactants may beprevented from penetrating a protective coating, another coupon ofporous low-k dielectric material was subjected to various conditions.The results are illustrated in FIG. 9, which is an illustrativegraphical representation 900 of thickness 902 by sample 904 inaccordance with embodiments of the present invention. The samples wereas follows:

dielectric+protective coating+cleaning agent+10% PEG-PPG-PEG (906);

dielectric+cross-linked protective coating+cleaning agent+10%PEG-PPG-PEG (908);

dielectric+protective coating+cleaning agent+TERGITOL TMN10 (910);

dielectric+cross-linked protective coating+cleaning agent+TERGITOL TMN10(912);

dielectric+protective coating+30% PEG-PPG-PEG (914);

dielectric+cross-linked protective coating+30% PEG-PPG-PEG (916);

dielectric+protective coating+40% PEG-PPG-PEG (918); and

dielectric+cross-linked protective coating+40% PEG-PPG-PEG (920).

For all samples a protective coating of a 0.05M solution PVA compoundhaving a molecular weight of approximately 13 to 23 kDa and being 89%hydrolyzed was applied to the coupon for approximately 60 s andsubsequently rinsed for approximately 60 s. For samples includingcross-linking, a 0.075M glutaraldehyde and 0.2M H₂SO₄ solution wasreacted with coupons at a reaction temperature of approximately 40° C.for a reaction time of approximately 90 s. A non-ionic surfactantcomposed of PEG-PPG-PEG at various concentrations and TERGITOL TMN10along with a cleaning agent composed of ESC784 by Advanced TechnologyMaterials Incorporated, of Danbury, Conn. diluted to 1:30 were reactedwith the dielectric having a non-cross-linked protective coating andwith the dielectric having a cross-linked protective coating indifferent combinations as noted above. Reaction times were approximately30 s. As illustrated, the data 930 demonstrates that the cross-linkedprotective coatings were effective in preventing penetration of allformulations utilizing non-ionic surfactants including, but not limitedto: 10% PEG-PPG-PEG, TERGITOL TMN10, 30% PEG-PPG-PEG, and 40%PEG-PPG-PEG as indicated by arrows 940, 942, 944, and 946 respectively.

Experiment 3

Experiment 3 demonstrates that co-polymerization of a PVA surfacemodifier prevents the degradation of a porous low-k dielectric materialin experiments where the co-polymerized PVA surface modifier iscross-linked and where the co-polymerized PVA surface modifier is notcross-linked. A coupon of porous low-k dielectric material was subjectedto various conditions. The results are illustrated in FIG. 10, which isan illustrative graphical representation 1000 of thickness 1002 bysample 1004 in accordance with embodiments of the present invention. Thesamples were as follows:

dielectric+cross-linked (A) protective coating+co-polymer (1006);

dielectric+cross-linked (A) protective coating+co-polymer+CP72B (1008);

dielectric+cross-linked (B) protective coating+co-polymer (1010);

dielectric+cross-linked (B) protective coating+co-polymer+CP72B (1012);

dielectric+protective coating+co-polymer (1014); and

dielectic+CP72B (1016).

For samples that include a protective coating, a 98% hydrolyzedPVA-co-siloxane compound was applied to the coupon for approximately 60s and subsequently rinsed for approximately 60 s. For samples includingcross-linking, condition (A) cross-linking was accomplished by rinsingthe protective coating with 0.4% HCl for approximately 60 s andsubsequently rinsed for approximately 60 s and condition (B)cross-linking was accomplished by rinsing the protective coating with0.04% HCl for approximately 60 s and subsequently rinsed forapproximately 60 s. For samples including washing with CoppeReady CP72Bby Air Products and Chemicals, Inc. of Allentown, Pa., which is anon-fluorinated, high performance copper/low-k CMP cleaning solution,the coupon was washed 15 times for approximately 30 s each time andsubsequently rinsed for approximately 60 s. As illustrated, the data1020 demonstrates that the PVA-co-siloxane protective coating survivedCP72B treatment without cross-linking Without being bound by theory, itis proposed that the co-polymer complex may form a covalent bond withsurface groups on the dielectric material. In some embodiments, otherco-polymers may be utilized without limitation including: co-ethylene,co-cation, co-anion (88% hydrolyzed), and co-anion (80% hydrolyzed).

Experiment 4

Experiment 4 demonstrates that a PVA surface modifier can prevent adecrease in dielectric constant of low-k dielectric materials andprotect the sometimes more sensitive low-k dielectric materials. Inorder to determine the effects of protective coatings under embodimentsof the present invention, several types of low-k dielectric materialswere subjected to a cleaning solution. The results are illustrated inFIG. 11, which includes illustrative graphical representations of %capacitance change by type in accordance with embodiments of the presentinvention. In graph 1100, the data illustrates % capacitance change 1102by type 1104 of several low-k dielectric materials namely: dielectric(k˜2.4) material 1106, dielectric (k˜2.4) material 1108, dielectric(k˜2.5) material 1110, dielectric (k˜2.6) material 1112, and dielectric(k˜3.0) material 1114. The materials were washed with CoppeReady CP72Bby Air Products and Chemicals, Inc. of Allentown, Pa., which is anon-fluorinated, high performance copper/low-k CMP cleaning solution forone minute.

In graph 1150, the data illustrates % capacitance 1152 by type 1154 ofseveral protectively coated low-k dielectric materials namely:dielectric (k˜2.4) material 1156, dielectric (k˜2.4) material 1158,dielectric (k˜2.5) material 1160, dielectric (k˜2.6) material 1162, anddielectric (k˜3.0) material 1164 in accordance with embodiments of thepresent invention. A 0.05M solution of a PVA compound having a molecularweight of approximately 12 to 25 kDa was applied to the materialswhereupon the materials were washed with CP72B for one minute.

In comparing graphs, graph 1150 indicates that a protective coating of aPVA compound is effective in protecting k values of hydrophobicdielectric materials 1156, 1158, and 1160. As may be appreciated, PVAreadily adsorbs with hydrophobic surfaces (e.g., dielectric materials1156, 1158, 1160, and 1164), which may explain these results.

In some embodiments, a substrate may be an electronic device selectedfrom a group consisting of: semiconductor devices, optoelectronicdevices, data storage devices, magnetoelectronic devices, magnetoopticdevices, molecular electronic devices, photovoltaic devices (e.g., solarcells), flat panel displays, MEMS, electroluminescent devices,photoluminescent devices, photonic devices, and packaged devices.

Embodiments described herein may be utilized to process a substrate madeof a variety of material. This is particularly so since the embodimentscan be implemented so that substrate material (e.g., a dielectricregion) is conditioned to have a particular hydrophilic property. Asused herein, conditioning of a material refers to modifying thehydrophilic characteristics of an exposed part of the material toachieve a desired wetability for any subsequent aqueous process. Inparticular, some embodiments may be utilized to process a semiconductorsubstrate as is commonly done in the manufacture of components for usein the electronics industry. Embodiments may also be utilized to processa substrate for use in the production of a flat panel display, whichsubstrates are now commonly made of silicon. In addition, embodimentsmay be utilized to process any type of semiconductor substrate, such as,for example, a silicon substrate, silicon-on-insulator substrate,silicon carbide substrate, strained silicon substrate, silicon germaniumsubstrate or gallium arsenide substrate.

Further, embodiments may be utilized to process a substrate of any shapeor size. For example, embodiments may be utilized to processsemiconductor substrates utilized in the production of electroniccomponents, which substrates are typically circular, as well as in theprocessing of substrates utilized in the production of flat paneldisplays, which substrates are typically rectangular or sheets ofsolar/photovoltaic cells. Embodiments may be utilized to process smallsemiconductor substrates having areas of less than approximately onesquare inch (in²) up to approximately 12 in² semiconductor substratescurrently utilized in the production of many electronic components. Ingeneral, there is no limit to the size of substrate that can beprocessed. Embodiments may also be utilized to process relatively largesubstrates that are utilized in the production of flat panel displays(now, commonly rectangular substrates on the order of approximately onesquare meter (m²), but, in some cases, larger) or sheets ofsolar/photovoltaic cells.

The above description of illustrated embodiments of the substrateprocessing systems is not intended to be exhaustive or to limit thesubstrate processing systems to any precise forms disclosed. While thisinvention has been described in terms of several embodiments, there arealterations, permutations, and equivalents, which fall within the scopeof this invention. It should also be noted that there are manyalternative ways of implementing the methods and apparatuses of thepresent invention. Furthermore, unless explicitly stated, any methodembodiments described herein are not constrained to a particular orderor sequence. Further, the Abstract is provided herein for convenienceand should not be employed to construe or limit the overall invention,which is expressed in the claims. It is therefore intended that thefollowing appended claims be interpreted as including all suchalterations, permutations, and equivalents as fall within the truespirit and scope of the present invention.

What is claimed is:
 1. A polyvinyl alcohol (PVA)-based surface modifiersolution comprising: PVA dissolved in water at a concentration between 1to 500 mM, wherein the PVA has a molecular weight in the range of 5 to200 kiloDaltons and wherein the PVA is 99% hydrolyzed.
 2. The polyvinylalcohol (PVA)-based surface modifier solution of claim 1, wherein theconcentration of the PVA is between 25 and 100 mM.
 3. The polyvinylalcohol (PVA)-based surface modifier solution of claim 1, wherein theconcentration of the PVA is 25 mM, the molecular weight is between 13and 23 kiloDaltons, and the PVA is 99% hydrolyzed.
 4. The polyvinylalcohol (PVA)-based surface modifier solution of claim 1 furthercomprising PVA compounds comprising thiol or amine.
 5. The polyvinylalcohol (PVA)-based surface modifier solution of claim 4 wherein the PVAcompounds comprising thiol comprise polyvinyl mercaptan.
 6. Thepolyvinyl alcohol (PVA)-based surface modifier solution of claim 4wherein the PVA compounds comprising amine comprise polyvinylamine. 7.The polyvinyl alcohol (PVA)-based surface modifier solution of claim 1wherein the PVA is cross-linked.
 8. The polyvinyl alcohol (PVA)-basedsurface modifier solution of claim 7 wherein the PVA is cross-linkedusing a cross-linking agent.
 9. The polyvinyl alcohol (PVA)-basedsurface modifier solution of claim 8 wherein the cross-linking agent isone of a glutaraldehyde solution, a dialdehyde solution, a sulfuric acidsolution, a maleic acid solution, a citric acid solution, a solution ofglutaraldehyde and sulfuric acid, or an ascorbic acid solution.
 10. Thepolyvinyl alcohol (PVA)-based surface modifier solution of claim 7wherein the PVA is cross-linked using non-chemical modification.
 11. Thepolyvinyl alcohol (PVA)-based surface modifier solution of claim 10wherein the non-chemical modification is one of deep ultra-violet cure,ebeam cure, or plasma cure.
 12. The polyvinyl alcohol (PVA)-basedsurface modifier solution of claim 1, wherein the concentration of thePVA is 0.5 M, the molecular weight is between 13 and 23 kiloDaltons, andthe PVA is 89% hydrolyzed.
 13. The polyvinyl alcohol (PVA)-based surfacemodifier solution of claim 1, wherein the PVA is co-polymerized withother polymers.
 14. The polyvinyl alcohol (PVA)-based surface modifiersolution of claim 13, wherein the co-polymers comprise one ofco-ethylene, co-cation, co-siloxane, or co-anion.